How to compare low pressure molding vs potting for electronics

Every electronic assembly that has to survive moisture, vibration, dust, chemicals, or temperature swings eventually faces the same design question: how should the board be protected? Two of the most common answers are potting and low pressure molding. Both encapsulate sensitive components, but they work in very different ways, and choosing the wrong one can mean unnecessary cost, slower production, or a product that fails in the field. This guide explains how to compare the two processes and pick the right one for your product.

What is potting?

Potting is a process in which a liquid two-part resin, typically epoxy, polyurethane, or silicone, is poured into a housing or shell that contains the circuit board. The resin flows around the components and then cures into a solid block that seals and protects the assembly. Because the resin has to be mixed, dispensed, de-gassed, cured, and finished, potting typically involves several process steps, and cure times commonly run from 24 to 72 hours. The cured material is essentially non-reworkable: if a component fails, the whole potted module usually has to be scrapped.

Potting still earns its place in many designs because it delivers strong mechanical protection and good thermal and chemical resistance. It remains a standard choice in power electronics, high-voltage modules, and other rugged applications where a rigid, solid block is genuinely required.

What is low pressure molding?

Low pressure molding (LPM) is an encapsulation process that uses a one-component thermoplastic hot-melt material, usually polyamide or polyolefin based. The material is heated until it flows, then injected into a mold around the electronics at low pressure, typically 1.5 to 40 bar. Because the pressure is gentle, even delicate PCBs, sensors, and fine wire connections are not damaged during molding. The material solidifies as it cools, usually within 20 to 45 seconds, and the finished part can be handled and tested almost immediately.

Unlike potting, LPM needs no separate housing: the molded material itself forms the protective shell. The process can be completed in as little as three steps, load, inject, and eject, and the thermoplastic remains reworkable, so a defective part can be re-melted and re-molded rather than scrapped.

Low pressure molding vs potting: head-to-head

The table below summarizes the key differences between the two encapsulation methods.

When to choose low pressure molding

Low pressure molding tends to win when any of the following matters to your project:

• Fast production. Encapsulation completes in seconds rather than hours of curing, which supports higher throughput and shorter lead times.
• Fewer parts. With no housing, gaskets, or fasteners, the bill of materials shrinks and inventory is easier to manage.
• Sensitive components. The low injection pressure protects delicate PCBs, solder joints, sensors, and fine wire bonds.
• Reworkability. Defective parts can be re-melted and re-molded instead of being thrown away.
• Waterproofing. IP67, IP68, and IP69K protection levels are achievable with the right mold design and material.
• Weight and size. The molded shell is lighter and more compact than a potted block inside a housing.

When potting is still the better choice

Potting is not obsolete, and it remains the right answer in several situations:

• The product must withstand extreme temperatures or very rugged, high-impact environments.
• A thick encapsulation layer is needed for high-voltage insulation.
• The design genuinely requires a rigid, solid block rather than a molded shell.
• The thermal or chemical properties of a specific resin are essential to the application.

A practical decision checklist

Before you commit to either process, work through these questions with your manufacturing partner:

1. What environment will the product face: moisture, chemicals, vibration, or temperature extremes?
2. What IP rating does the end application actually require?
3. How many units do you produce per year, and what cycle time can you afford?
4. Do you need to rework defective units, or is scrapping acceptable?
5. Can the product accept a housing, or is weight and size critical?
6. What is the full operating temperature range of the device?

How Farway can help

Farway Electronic is an electronic manufacturing services provider in Shenzhen that offers both low pressure molding for electronics and conformal coating as part of a one-stop manufacturing chain covering PCB production, component sourcing, SMT, DIP, PCBA OEM, testing, and finished-product assembly.

With four low-pressure injection moulding machines, Farway supports applications from medical and industrial sensors to LED lighting, mobile-phone and power batteries, connector harnesses, circuit boards, and microswitches. Its automated conformal-coating line handles boards up to 550 mm by 470 mm, and its PCBA testing capabilities, including X-ray, ICT, FCT, thermal imaging, and high- and low-temperature testing, make sure encapsulated boards are verified before they ship.

Farway is certified to ISO 9001, ISO 13485, IATF 16949, and ISO 14001, and has served more than 100 customers across more than 20 countries and regions. Whether you are still comparing processes or ready to move to production, the Farway engineering team can help you evaluate potting, low pressure molding, and conformal coating against your product requirements.